This paper focuses on physical and social spaces of nocturnal Istanbul such as streets, neighborhoods, commercial centers, and entertainment dwellings. It contends that the implementation of artificial street lighting transformed night-time geography in which different historical actors of the Ottoman Empire - be they ruling authorities, merchants, commoners or marginal groups - encountered one another through the second half of the nineteenth century. By exploring the use and regulations of public places and social spaces, this paper shows how the Ottoman ruling authorities established norms and forms of social containment under the discourse of urban order, public security, and public morality. In addition, it evidences how marginal groups such as rebels, criminals, ramblers or prostitutes made use of this new night-time geography and how they reacted against the municipal implementations produced under the discourse of lower class vice and elite fear in the late 19th and early 20th centuries. This study will address a series of administrative, institutional, and organizational transformations regarding the changing urban image of the 19th-century Ottoman imperial capital. First, it will examine how the implementation of artificial lighting changed the urban settlement and how it transformed the night-time geography by making it more penetrable. Then, it will analyze how city lights played a crucial role in the evolution of urban social morphology and the emergence of a distinct urban culture composed of subjective experiences of different historical actors such as state authorities, elite families, and marginal groups such as criminals, ramblers, or prostitutes. It examines who was socially and physically included in and excluded from this urban settlement and what was the reason behind marginalization and configuration of “dangerous classes” under the discourse of urban order and public morality. This paper also aims to speculate on how people incorporated this new technology into their daily lives and how it transformed people’s perception of time and space in nocturnal Istanbul.